PROJECT SUMMARY/ABSTRACT We propose a 3-year study to adapt and pilot test a motivational network interview (MNI) intervention for formerly homeless transition age youth (TAY; 18-25 year olds) who are in the process of transitioning to a Housing First (HF) program. The goal of HF programs is to house individuals first ? without any preconditions ? and then provide whatever supportive services they might need. Many homeless TAY enter HF programs with substance use problems, while also trying to navigate substantial changes to their social environment (often leaving old relationships behind, and forming new relationships where they now live). This transition period presents a unique opportunity to implement a brief risk reduction intervention for these TAY that will both reduce their substance use, and increase the permanent pro-social connections with adults that can provide them with ongoing support and stability. In this pilot RCT, TAY residents within their first two weeks of entering a HF program will be randomized to receive the MNI or to usual case management. The MNI involves four 30- minute sessions, delivered by the resident's case manager as part of their regular, ongoing support meetings. Case managers will be trained to deliver the MNI using a motivational interviewing style and with the aid of an electronic tablet device. The tablet will guide them in collecting information about the residents' social networks and then display diagrams highlighting various aspects of the residents' networks. The case managers will then use motivational interviewing techniques to guide residents to think about how their network currently functions, how they would like it to function, and what steps they can take to make changes necessary to achieve goals related to reducing their substance use and enhancing their permanent supportive connections. If effective, this brief MNI will provide a valuable tool for researchers and clinicians working with substance using homeless TAY.